cortex_m: Discover the AP to use, just like Cortex-A

This required fixing the AP ID parsing in dap_find_ap() to
match IHI0031C. The AXI type was added too.

Change-Id: I44577a7848df37586e650dce0fb57ac26f5f858c
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/3146
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>

3 files changed, 18 insertions, 7 deletions

diff --git a/src/target/arm_adi_v5.c b/src/target/arm_adi_v5.c
index 53c0c4e1..3a81784e 100644
--- a/src/target/arm_adi_v5.c
+++ b/src/target/arm_adi_v5.c
@@ -825,9 +825,10 @@ int dap_find_ap(struct adiv5_dap *dap, enum ap_type type_to_find, uint8_t *ap_nu
 		 * 31-28 : Revision
 		 * 27-24 : JEDEC bank (0x4 for ARM)
 		 * 23-17 : JEDEC code (0x3B for ARM)
-		 * 16    : Mem-AP
-		 * 15-8  : Reserved
-		 *  7-0  : AP Identity (1=AHB-AP 2=APB-AP 0x10=JTAG-AP)
+		 * 16-13 : Class (0b1000=Mem-AP)
+		 * 12-8  : Reserved
+		 *  7-4  : AP Variant (non-zero for JTAG-AP)
+		 *  3-0  : AP Type (0=JTAG-AP 1=AHB-AP 2=APB-AP 4=AXI-AP)
 		 */
 
 		/* Reading register for a non-existant AP should not cause an error,
@@ -835,11 +836,12 @@ int dap_find_ap(struct adiv5_dap *dap, enum ap_type type_to_find, uint8_t *ap_nu
 		 */
 		if ((retval == ERROR_OK) &&                  /* Register read success */
 			((id_val & 0x0FFF0000) == 0x04770000) && /* Jedec codes match */
-			((id_val & 0xFF) == type_to_find)) {     /* type matches*/
+			((id_val & 0xF) == type_to_find)) {      /* type matches*/
 
 			LOG_DEBUG("Found %s at AP index: %d (IDR=0x%08" PRIX32 ")",
 						(type_to_find == AP_TYPE_AHB_AP)  ? "AHB-AP"  :
 						(type_to_find == AP_TYPE_APB_AP)  ? "APB-AP"  :
+						(type_to_find == AP_TYPE_AXI_AP)  ? "AXI-AP"  :
 						(type_to_find == AP_TYPE_JTAG_AP) ? "JTAG-AP" : "Unknown",
 						ap, id_val);
 
@@ -851,6 +853,7 @@ int dap_find_ap(struct adiv5_dap *dap, enum ap_type type_to_find, uint8_t *ap_nu
 	LOG_DEBUG("No %s found",
 				(type_to_find == AP_TYPE_AHB_AP)  ? "AHB-AP"  :
 				(type_to_find == AP_TYPE_APB_AP)  ? "APB-AP"  :
+				(type_to_find == AP_TYPE_AXI_AP)  ? "AXI-AP"  :
 				(type_to_find == AP_TYPE_JTAG_AP) ? "JTAG-AP" : "Unknown");
 	return ERROR_FAIL;
 }
diff --git a/src/target/arm_adi_v5.h b/src/target/arm_adi_v5.h
index 32b72395..85b62243 100644
--- a/src/target/arm_adi_v5.h
+++ b/src/target/arm_adi_v5.h
@@ -279,9 +279,10 @@ struct dap_ops {
  * Access Port types
  */
 enum ap_type {
-	AP_TYPE_AHB_AP  = 0x01,  /* AHB Memory-AP */
-	AP_TYPE_APB_AP  = 0x02,  /* APB Memory-AP */
-	AP_TYPE_JTAG_AP = 0x10   /* JTAG-AP - JTAG master for controlling other JTAG devices */
+	AP_TYPE_JTAG_AP = 0x0,  /* JTAG-AP - JTAG master for controlling other JTAG devices */
+	AP_TYPE_AHB_AP  = 0x1,  /* AHB Memory-AP */
+	AP_TYPE_APB_AP  = 0x2,  /* APB Memory-AP */
+	AP_TYPE_AXI_AP  = 0x4,  /* AXI Memory-AP */
 };
 
 /**
diff --git a/src/target/cortex_m.c b/src/target/cortex_m.c
index ec5caa28..7a7194a1 100644
--- a/src/target/cortex_m.c
+++ b/src/target/cortex_m.c
@@ -1903,6 +1903,13 @@ int cortex_m_examine(struct target *target)
 	struct adiv5_dap *swjdp = cortex_m->armv7m.arm.dap;
 	struct armv7m_common *armv7m = target_to_armv7m(target);
 
+	/* Search for the MEM-AP */
+	retval = dap_find_ap(swjdp, AP_TYPE_AHB_AP, &armv7m->debug_ap);
+	if (retval != ERROR_OK) {
+		LOG_ERROR("Could not find MEM-AP to control the core");
+		return retval;
+	}
+
 	/* Leave (only) generic DAP stuff for debugport_init(); */
 	swjdp->ap[armv7m->debug_ap].memaccess_tck = 8;